EXPTREE - Editorial

In the mentioned paper:

The number of nodes of degree, d in all the trees in T,

  1. = the number of occurrences of d in all the sequences in I,
  2. = the number of occurrences of runs of exactly d(‘s (or equivalently
    d)‘s) in all the expressions in P(Parenthesis representation).

How can the 2nd statement be justified, say suppose d=1, then according to 2nd statement, number of nodes of degree 1 would be all ‘(’ brackets and that would n, which doesn’t seem to be true.

Am I missing something which is not so obvious?